DIPHOSPHONIC ACID DERIVATIVES AND THEIR MANUFACTURE AND USE

摘要

Novel diphosphonic acid derivatives of the general formula I (I) (in which X represents cyano, 2-cyanoethyl or 3-amino-propyl and Y represents H or X and Y together represent dimethylaminomethylene and R1 to R4 each represents H or C1-C4-alkyl, X not representing cyano when R1 to R4 each represents ethyl) and physiologically tolerable salts of such compounds containing a free acid group, and processes for their manufacture.